BONE SCREW

Abstract

Method for manufacturing a bone pin for connection to a bone, particularly for fixing an implant to a bone, the bone pin having an implant contacting part arranged to contact the implant in connected situation and a bone contacting part arranged to engage the bone in connected situation, wherein the method comprises the steps of:—providing bone information which is indicative for the bone which the bone contacting part is arranged to engage;—providing a bone contacting part which is customized on the basis of the bone information for engaging said bone;—providing an implant contacting part; and—assembling the bone contacting part and the implant contacting part for manufacturing the pin.

Claims

1. Method for manufacturing a bone pin for connection to a bone, particularly for fixing an implant to a bone, the bone pin having an implant contacting part arranged to contact the implant in connected situation and a bone contacting part arranged to engage the bone in connected situation, wherein the method comprises the steps of: providing bone information which is indicative for the bone which the bone contacting part is arranged to engage; providing a bone contacting part which is customized on the basis of the bone information for engaging said bone; providing an implant contacting part; and assembling the bone contacting part and the implant contacting part for manufacturing the pin.

2. Method according to claim 1, wherein the bone contacting part is customized in terms of length, porosity, material, threading, diameter or core diameter, or a combination thereof.

3. Method according to claim 1 or 2, wherein the pin comprises at least two different bone contacting parts arranged for engaging at least two different parts of the bone in connected situation, the different parts of the bone having different bone characteristics, wherein the method further comprises providing bone information which is indicative for the bone characteristics of both parts of the bone, further comprising providing bone contacting parts which are customized on the basis of the bone information for engaging said different bone parts.

4. Method according to claim 3, wherein the different bone contacting parts extend in the longitudinal direction of the pin with respect to each other.

5. Method according to any of the preceding claims, wherein the step of providing bone information comprises (intra-)operative measurements

6. Method according to any of the preceding claims, wherein the step of providing bone information comprises medical imaging for obtaining the bone characteristics of at least the bone surrounding the bone contacting parts of the pin.

7. Method according to claim 6, wherein the bone information comprises bone density data.

8. Method according to claim 6 or 7, further comprising the step of providing a pin having length determined on the basis of the bone information, wherein the pin is designed to have sufficient length such that the bone contacting parts thereof extend through at least two different types of bone.

9. Method according to any of the preceding claims, wherein the step of providing the bone contacting parts comprises any of the following steps of: a. providing a bone contacting part with threading in case the bone part to be engaged is cortical bone or other bone with a high bone mineral density; b. providing a bone contacting part having a porous microstructure in case the bone part to be engaged is trabecular bone or other bone with a lower bone mineral density.

10. Method according to at least claims 3, 8 and 9, wherein the pin comprises at least one bone contacting part provided with threading and at least one bone contacting part having a porous microstructure.

11. Method according to any of the preceding claims, further comprising the step of providing a connecting part, wherein a connecting part of the pin is arranged to interact with another pin and is thereto provided with a receptacle for receiving another pin, wherein the step of assembling further comprises assembling the connecting part.

12. Method according to claim 11, wherein the receptacle comprises a through hole for receiving another pin.

13. Method according to any of the preceding claims, wherein at least the step of providing the bone contacting part, preferably also the step of assembling or manufacturing the pin, comprises using a three-dimensional printing technique.

14. Bone pin for fixing an implant to a bone, the bone pin having an implant contacting part arranged to contact the implant in connected situation and a bone contacting part arranged to engage the bone in connected situation, wherein the bone contacting part is customized for engaging said bone.

15. Bone pin according to claim 14, comprising a plurality of bone contacting parts, each customized for engaging said bone, wherein at least two of the bone contacting parts have different properties in terms of length, porosity, material, threading, diameter or core diameter, or a combination thereof.

16. Bone pin according to claim 14 or 15, wherein the bone contacting part is at least partly manufactured from a porous material.

17. Bone pin according to claim 16, wherein the bone pin comprises at least one bone contacting part provided with threading and at least one bone contacting part having a porous microstructure.

18. Bone pin according to claim 16, wherein the porous bone contacting part is provided with threading.

19. Bone pin according to claim 18, further comprising a reinforcing structure for reinforcing at least the porous bone contacting part.

20. Bone pin according to any of the preceding claims, further comprising a connecting part, wherein a connecting part of the pin is arranged to interact with another pin and is thereto provided with a receptacle for receiving another pin.

21. Bone pin according to claim 20, wherein the receptacle comprises a through hole for receiving another pin.

22. Bone pin according to any of the preceding claims, wherein at least the bone contacting part, preferably whole the pin, is manufactured using a three-dimensional printing technique.

23. Kit of parts for assembling a bone pin according to any of the preceding claims, comprising an implant contacting part and a bone contacting part, wherein the implant contacting part and/or the bone contacting part is provided with connecting means for interconnecting the parts.

Description

[0043] The present invention is further illustrated by the following Figures, which show a preferred embodiment of the device according to the invention, and are not intended to limit the scope of the invention in any way, wherein:

[0044] FIG. 1 schematically shows the different parts of the screw according to the invention;

[0045] FIG. 2 shows two embodiments of the invention;

[0046] FIG. 3 shows the left screw of FIG. 2 in connected situation; and

[0047] FIGS. 4-9 schematically show further embodiments of the screw according to the invention.

[0048] In FIG. 1, the basic configuration of a bone screw 10 according to the invention is shown. The screw 10 is arranged to fixate an implant 100, see the right figure, to the bone B. The implant 100 in this example comprises a plate-like solid structure 100a and a porous structure 100b for bone ingrowth. The implant 100 is further provided with a tapering hole 101 for receiving an accordingly tapered head H of the screw 10.

[0049] The screw 10 is further provided with a sharp point T at the distal end, i.e. seen along the longitudinal direction L of the screw 10. In between the head H and the cylindrical part distally therefrom which are arranged to contact the implant 100 in connected state, hereafter referred to as the implant contact part of the screw 10, is provided a bone contacting part C, in this example subdivided in three part 1-3, although it will be apparent that the invention is not limited to a particular number of subdivisions of the bone contacting part C. Dividing the bone contacting part C in different sections or simply by providing a plurality of bone contacting parts 1-3 along the length L of the screw 10, allows customization of the screw 10 to varying bone characteristics the different parts are to engage in connected situation.

[0050] In the examples of FIG. 2 for instance, three bone contacting parts 1a, 2a, 3a and 1b, 2b and 3b are provided. The part 1a of the first example (on the left) is for instance provided with a thread 4 having a first pitch, while the third part 3a is provided with a thread 4 having a different, in this example larger, pitch. In between the parts 1a and 3a is provided a porous part 2a which is arranged to promote ingrowth in connected state. A similar screw is for instance shown in connected situation in FIG. 3. It is visible that the first and third parts 1a and 3a (in this example provided with a thread 4 having the same pitch) engage cortical bone B1, while the inner porous part 2a engage trabecular bone B2. The screw as shown in FIG. 3 is specifically designed to allow this engagement. More specifically, for the design of the screw, bone information, in this example bone mineral density data of the bone was available, such that the length of the screw and the division of the bone contacting parts 1a-3a could be chosen such that two threaded parts 1a and 3a engage cortical bone B1, while the porous part 2a engages spongy bone B2. The screw 10 is thus customized to the patient's bone into which the screw is designed to be inserted. The variant on the right of FIG. 2 varies in that the diameter of the third part 3b varies along the length L. Further examples of varying diameters of the parts 1c-3c are visible in FIG. 4. In the right of FIG. 4 it is further visible that also a single bone contacting part C1, in this example with decreasing diameter towards the tip T is possible.

[0051] Also in the example of FIG. 5a the bone contacting part C2 is provided. Only in this example, this part is porous while this part is also provided with a thread 4. The tip T is preferably solid. Although it is not visible in this figure, the inner part of the bone contacting part C2 is provided with a solid structure to provide sufficient strength to the screw. FIG. 5b shows an example of bone contacting parts 3c, 4c which extend under an angle with respect to the longitudinal axis of the screw. The components 3c and 4c, of which the part 3c is porous and of which part 4c is solid, may for instance extend helically around the longitudinal axis such that the parts 4c form a threading 4.

[0052] In the example of FIGS. 6a and 6b, a set of screws is shown which are arranged to cooperate and engage in connected situation. The first screw 10a in FIG. 6a is hereto, next to two not further specified bone contacting parts 1 and 3, provided with a part D which is arranged to connect to another screw 10b. The connecting part D is hereto provided with a through hole 6, which diameter d1 corresponds to a diameter d2 of the part 1a with which the connecting part D is arranged to engage. More specifically, during a pre-operative planning of the connection of an implant, the screws as shown in FIG. 6a are planned to intersect such that a part 1a extends through the hole 6. The hole 6 and/or the part 1a may thereto be provided with threading 4, 4a to enhance the fixation. As an alternative as shown in FIG. 6B, the screw contacting part D may be provided with a (locally) smooth surface, such that the second screw 10b can pass without substantial interference.

[0053] The screw according to the invention is preferably manufactured as a whole using a three-dimensional printing technique. The screw is thereto preferably first designed, in particular on the basis of image data as shown in FIG. 3, and subsequently printed. In particular the porous structures are very suitable to be printing in this way.

[0054] With reference to FIG. 7, it is however also possible that the different parts, for instance the bone contacting part C and main part 11, for instance provided with the head H and the most distal part of the tip and interconnected with a core 12, are provided separately. During an operation, the user may select a suitable bone contacting part, or a plurality thereof to combine, and assemble the screw 10a by inserting the core 12 into the correspondingly shaped hole 13, in terms of diameters d2 and d3.

[0055] An alternative is shown in FIG. 8, wherein different parts of the screw 10a can be assembled by threading 7a, 7b, 7c and 7d, the threading of which is in the same direction of the treads of the bone contacting parts 1 and 3 to prevent loosening of the parts upon screwing of the screw into the bone. Alternative connections may be used, such as a bayonet fitting.

[0056] In FIG. 9, an embodiment of a pin is shown wherein the different bone contacting parts 1-3d extend radially with respect to each other and the longitudinal axis of the pin. This pin can either be screwed or inserted in the bone. The parts are hereto cylindrically shaped and manufactured to closely fit each other in the radial direction. Each of the parts 1-3d may have different properties adapted to the bone the parts are arranged to contact and/or the function the parts 1-3d have. The lengths are adjusted accordingly. It is for instance possible that first a solid part 1d, for instance provided with a tip (not shown) is inserted and that subsequently the second part 2d is advanced over the first part 1d. This part may for instance be a porous part for engaging porous bone. The last part 3d may for instance again be a solid part for engagement with an implant.

[0057] It is also possible that an outer part 3d has a length which is greater than an inner part. This outer part 3d then preferably extends beyond said inner parts, such that a hollow core at the tip is formed which can be filled with bone by bone ingrowth. A similar connection with improved bone-ingrowth can be obtained if after insertion of for instance the combination of FIG. 9, an inner part 1d is withdrawn after insertion. This part then may have a length similar to for instance the more outer part 2d. This hollow core may then be filled with bone, which improves the connection of the pin over time.

[0058] The present invention is not limited to the embodiment shown, but extends also to other embodiments falling within the scope of the appended claims.